How do aquasensors work?

Do softeners with aquasensors, and water meters, just measure/calculate hardness that passes into the softener? Are the sensors part of the valve? Where and when exactly do they sense? I would assume the calculation needs to be adjusted periodically as the resin ages. Can an additional sensor of the same type detect if the softened water starts showing hardness? Can the sensor tell the difference between Ca/Mg in the water versus Na.

How do the sensors actually measure the water hardness? (Something electrical I'm guessing. Is it just conductivity?) How accurate and sensitive are they when working properly?

Yep, every Culligan aquasensor unit I have run across has been bypassed. In fact, I've bypassed a bunch of them myself. As for how they work, I believe that they do measure electrical resistance which changes with mineral content. Even when one is working I always wondered just how accurate they could be and of course, being made by Culligan, unless you are a dealer getting information from them is impossible. Almost as hard as getting anything out of Kinetico

I figured they were gimmicky or they would likely be much more common.

I found a Culligan manual that answered a number of my questions. (Their programming seems much more complicated than Clack.) The sensor is embedded in the resin and detects when it's starting to get exhausted. It also detects when slow rinse has pushed the remaining brine through so the next cycle can start a bit earlier.

If the sensors gradually fail, it seems they would detect less conductivity (thus less hardness) than is actually there, so less frequent regenerations I'm assuming. But is seems override settings for calender or water volume or maximum grain capacity can easily cover for it.

Why do the sensors have to be bypassed? Do customers report their treated water being hard? What are the symptoms of a failing sensor? Doesn't Culligan bother to set the overrides?

Yes. But what does Culligan (or others) do about it? If a customer happens to notice hard water, does Culligan sell them a new softener when it's just a failing sensor?

Can the sensors be removed to be inspected and cleaned or replaced, or does Culligan just reprogram the unit to use water metering?

It seems a system could be designed to use the sensor to regenerate with, say, 6lbs. Otherwise if it's been a couple more days, or few more hundred gallons, than expected, fall back to metered regeneration with 8lbs and turn on an indicator light. Everything is still fine and the customer can decide if they want to do anything about it.

Correction: A couple more days might go by without the sensor failing and a calender override could take care of that. But if a few hundred gallons more than expected are used, that might indicate a failing sensor and metered usage could take over with a little more salt and little higher gallon capacity to trigger regeneration.

The system is as good as the sensor.... and will last as long as the sensor is good.

More times than not when the sensor goes bad the system fails. Replace the sensor is easier said than done.

At one time and still may be this way the Culligan sensor was at the end of a line that was set in the tank when the gravel was put in and then the resin added, so if the senor goes out then the media has to be removed and a new sensor put in. That is if the designe has not changed.

If the sensors are through the side of the tank , then care .... real care is needed not to frack the tank in changing out the sensors.....

For me it looks to be more of a pain than a savings.

Blue Tooth is great when it works, but if it does not work because of one line of code some place then............ it is a pain.